Coronary heart disease (CHD) is the leading cause of death in the United States and the western world. Coronary heart disease accounts for almost two-thirds of male deaths during that period of life (30-64 years) when responsibilities to family and society are the greatest. Approximately one-third of individuals dying of coronary heart disease succumb immediately after coronary occlusions; one-third die within a few hours; and only one-third receive the benefits of hospital therapy. Of all individuals sustaining their first myocardial infarction, more than half have had neither preceding signs nor symptoms of coronary heart disease.
During the past two years, coronary vein-graft by-pass surgery has been demonstrated to be an effective therapeutic modality of wide applicability. Because over 70% of all coronary artery stenoses occur in the first 4 cm. of the coronary arterial tree, a high percentage of all coronary lesions can be surgically by-passed with a low mortality and high patency rate.
Extensive epidemiological studies have delineated those factors (hypercholesterolemia, hypertension, obesity, and heavy smoking) that are statistically correlated with an increased incidence of coronary heart disease. But while a patient may be well advised to remove himself from the higher risk group by appropriately altering his manner of living, these indices cannot for any given patient furnish information concerning the existence of coronary stenotic lesions nor furnish a basis for clinical decisions regarding therapeutic intervention.
Electrocardiograhic stress testing has been suggested as a means for screening individuals for significant coronary lesions. However, in a large prospective study in which subjects underwent repeated testing, the sensitivity of this test was found to be too low (only 30%) to be adequate.
At present, coronary arteriography yields more useful information about the state of the coronary arteries than any other technique. However, in a large cooperative study, the incidence of major complications was 2% and the mortality rate was 0.23%. In addition to the dangers, the procedure is painful, expensive, and time-consuming. For these reasons, coronary angiography is not performed upon asymptomatic individuals and is not suitable for screening large populations.
The above considerations highlight the importance of the subject invention which furnishes the capability for detecting the extent, location and severity of coronary stenotic lesions by means of apparatus operating external to the body, thereby identifying, by means suitable for screening large populations, candidates for remedial coronary surgery and other therapeutic measures.